ath9k: fix stopping tx dma on reset

In some situations, stopping Tx DMA frequently fails, leading to messages
like this:

ath: Failed to stop TX DMA in 100 msec after killing last frame
ath: Failed to stop TX DMA!

This patch uses a few MAC features to abort DMA globally instead of iterating
over all hardware queues and attempting to stop them individually.
Not only is that faster and works with a shorter timeout, it also makes the
process much more reliable.

With this change, I can no longer trigger these messages on AR9380,
and on AR9280 they become much more rare.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

3 files changed, 35 insertions, 8 deletions

diff --git a/drivers/net/wireless/ath/ath9k/mac.c b/drivers/net/wireless/ath/ath9k/mac.c
index c75d40fb86f1..58aaf9ab0920 100644
--- a/drivers/net/wireless/ath/ath9k/mac.c
+++ b/drivers/net/wireless/ath/ath9k/mac.c
@@ -143,6 +143,34 @@ bool ath9k_hw_updatetxtriglevel(struct ath_hw *ah, bool bIncTrigLevel)
 }
 EXPORT_SYMBOL(ath9k_hw_updatetxtriglevel);
 
+void ath9k_hw_abort_tx_dma(struct ath_hw *ah)
+{
+        int i, q;
+
+        REG_WRITE(ah, AR_Q_TXD, AR_Q_TXD_M);
+
+        REG_SET_BIT(ah, AR_PCU_MISC, AR_PCU_FORCE_QUIET_COLL | AR_PCU_CLEAR_VMF);
+        REG_SET_BIT(ah, AR_DIAG_SW, AR_DIAG_FORCE_CH_IDLE_HIGH);
+        REG_SET_BIT(ah, AR_D_GBL_IFS_MISC, AR_D_GBL_IFS_MISC_IGNORE_BACKOFF);
+
+        for (q = 0; q < AR_NUM_QCU; q++) {
+                for (i = 0; i < 1000; i++) {
+                        if (i)
+                                udelay(5);
+
+                        if (!ath9k_hw_numtxpending(ah, q))
+                                break;
+                }
+        }
+
+        REG_CLR_BIT(ah, AR_PCU_MISC, AR_PCU_FORCE_QUIET_COLL | AR_PCU_CLEAR_VMF);
+        REG_CLR_BIT(ah, AR_DIAG_SW, AR_DIAG_FORCE_CH_IDLE_HIGH);
+        REG_CLR_BIT(ah, AR_D_GBL_IFS_MISC, AR_D_GBL_IFS_MISC_IGNORE_BACKOFF);
+
+        REG_WRITE(ah, AR_Q_TXD, 0);
+}
+EXPORT_SYMBOL(ath9k_hw_abort_tx_dma);
+
 bool ath9k_hw_stoptxdma(struct ath_hw *ah, u32 q)
 {
 #define ATH9K_TX_STOP_DMA_TIMEOUT       4000    /* usec */
diff --git a/drivers/net/wireless/ath/ath9k/mac.h b/drivers/net/wireless/ath/ath9k/mac.h
index 04d58ae923bb..d37c6d413be1 100644
--- a/drivers/net/wireless/ath/ath9k/mac.h
+++ b/drivers/net/wireless/ath/ath9k/mac.h
@@ -677,6 +677,7 @@ void ath9k_hw_cleartxdesc(struct ath_hw *ah, void *ds);
 u32 ath9k_hw_numtxpending(struct ath_hw *ah, u32 q);
 bool ath9k_hw_updatetxtriglevel(struct ath_hw *ah, bool bIncTrigLevel);
 bool ath9k_hw_stoptxdma(struct ath_hw *ah, u32 q);
+void ath9k_hw_abort_tx_dma(struct ath_hw *ah);
 void ath9k_hw_gettxintrtxqs(struct ath_hw *ah, u32 *txqs);
 bool ath9k_hw_set_txq_props(struct ath_hw *ah, int q,
                             const struct ath9k_tx_queue_info *qinfo);
diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index e16136d61799..bb1d29e90eb1 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -1194,16 +1194,14 @@ bool ath_drain_all_txq(struct ath_softc *sc, bool retry_tx)
         if (sc->sc_flags & SC_OP_INVALID)
                 return true;
 
-        /* Stop beacon queue */
-        ath9k_hw_stoptxdma(sc->sc_ah, sc->beacon.beaconq);
+        ath9k_hw_abort_tx_dma(ah);
 
-        /* Stop data queues */
+        /* Check if any queue remains active */
         for (i = 0; i < ATH9K_NUM_TX_QUEUES; i++) {
-                if (ATH_TXQ_SETUP(sc, i)) {
-                        txq = &sc->tx.txq[i];
-                        ath9k_hw_stoptxdma(ah, txq->axq_qnum);
-                        npend += ath9k_hw_numtxpending(ah, txq->axq_qnum);
-                }
+                if (!ATH_TXQ_SETUP(sc, i))
+                        continue;
+
+                npend += ath9k_hw_numtxpending(ah, sc->tx.txq[i].axq_qnum);
         }
 
         if (npend)